1. Field of the Invention
The present invention concerns a device arranged to permit an air flow from an environment to an inner space of a member, comprising a passage through a wall section of said member.
2. Description of the Prior Art
It is known to provide such air inlet devices in connection with milking members. For example U.S. Pat. No. 5,076,211 shows a teat cup claw with such an air inlet formed by a simple opening, which extends through a wall section of the teat cup claw. The object by such an air inlet is to create a flow through an inner space of the teat cup claw which inner space is connected to a vacuum pump in order to enable transportation of the milk, which is present in the inner space. At the same time, it is desirable to mix as little air as possible with the milk in order to be able to maintain a high quality of the latter. That means that the opening is to be made small, i.e. with a small diameter which usually may be between 0.5 and 1 mm.
However, such air inlets have the drawback that they often become filled up with dirt, muck, insect legs or dried milk. Since milk easily is accumulated in the area of the air inlet, it attracts flies and other insects. It thereby happens that a fly gets stuck with a leg in the air inlet opening, which results in that the opening will finally be completely closed.
In addition to the risk of being filled up, such relatively small openings are difficult and expensive to produce in for example a teat cup claw of steel but it is also difficult to make such a small opening in a teat cup claw of plastic, since the opening is very small in relation to the teat cup claw.
The object of the present invention is to achieve an air inlet which does not have the drawbacks mentioned above. In particular, an air inlet is aimed at which has a reduced tendency of being filled up. Furthermore, an air inlet is aimed at which is easy to clean.
This object is obtained by the device initially defined which is characterized in that the wall section comprises a convex surface area which faces said environment, wherein the passage extends through the surface area. Preferably, the convex surface area is designed with such a convexity that an accumulation of substances on the surface area is prevented. Consequently, such substances, such as dirt and other particles or liquids, for example milk, will not be accumulated in the area around the passage, since particles of dirt or liquids will xe2x80x9cflowxe2x80x9d over the convex surface away from the passage. Consequently, the convex surface area, with the passage, will not be so attractive for flies and other insects.
According to a preferred embodiment of the invention the passage extends through an essentially central part of the surface area. Furthermore, the surface area is advantageously continuously convex. By these embodiments, the production of the device according to the invention is facilitated.
According to a further embodiment of the invention the convex surface area extends upwards from the wall section. Thereby, it is facilitated in an even higher degree for particles of dirt and liquids to flow away from the passage. Furthermore, the passage and the convex surface area may by such a design be cleaned in a simple manner, by simply passing over the surface portion with a finger.
According to a further embodiment, the passage is defined by a wall portion and the passage is tapered in a direction from the inner space to said environment. By such a tapered, preferably conical, design of the passage, it is guarantied that possible dirt which penetrates the passage will be sucked into the inner space in a simple manner and in this way it is guarantied that the passage is always open.
According to a further embodiment of the invention, the device comprises an element comprising the convex surface area and being arranged to be provided in an aperture of said wall section. In this way, the convex surface area and the passage may constitute a small unit, which may be separately produced and which may be assembled with for example a teat cup claw or a teat cup. Advantageously, said element is arranged to be able to be pushed into and pulled out from said aperture. In this way, the element may in a simple manner be changed if it after all would have been filled up. This embodiment also makes it possible to change between passages with different dimensions for different occasions. Advantageously, said element is substantially tubular, wherein it may comprise an end portion with an outer surface which forms the convex surface area.
According to a further embodiment of the invention, a sealing member is provided between said element and said aperture. In this way, it is guarantied that no air may pass through between the element and the wall of the aperture. Advantageously, the sealing member may also be tubular and furthermore, it may comprise a flange, which extends substantially radially outwards and is arranged to abut said wall section. Advantageously, the sealing member is fixedly provided at said element. The sealing member may thereby be made of a rubber-like material, which is melted together with said element. The element may thereby be made of a thermoplastic resin, which comprises sulphur.
In a preferred application of the invention, said member comprises a component of a milking plant. This component may comprise a milking member, such as a teat cup claw or a teat cup.